Photopolymers having molecular orientations that can be established by exposure to irradiation with linearly polarized ultraviolet light have been developed for use in aligning liquid crystal layers. For example, Chigrinov et al., U.S. Pat. No. 5,389,698, discloses orientable polymers based on polyvinyl cinnamate that can be used as optical retarders or liquid crystal alignment layers. Schadt et al., U.S. Pat. No. 5,602,661, discloses using photo-orientable polymer networks (PPNs) with certain cross-linked liquid crystal monomers to provide a fixed, structured orientation. Schadt also discloses liquid crystal materials consisting of mixtures of liquid crystal monomers and functional dichroic chromophores. Polarization masks for transfer of polarization patterns to PPN layers are disclosed by Seiberle, U.S. Pat. No. 6,496,239. The above patents provide additional details of conventional aspects of device structures, fabrication methods, and materials, and are incorporated herein in their entireties to provide at least this additional information.
While PPN materials have been described and structures based on such materials are described in the above-cited patents, the application of PPN materials for other purposes has heretofore been unappreciated. Novel and non-obvious uses and applications are disclosed below.